OREA offers both exam formats. Just choose which one you want when booking an examination. The only difference between them: Instead of circling answers on a Scantron card, you simply click on one of four screen answer options. Rather than using the exam booklet to make any notes or do calculations, OREA provides note paper. However, the note paper stays in the exam room when you're finished.
The big benefit of online? Marks within 24 hours. Computer-based exams are only offered during the week. Paper-based are on Saturdays.
The biggest risk with online? Rushing through the questions and not carefully and methodically checking your answers before submitting them electronically.